<em>class</em> <s>MyObserver</s> <em>extends</em> <u>NavigatorObserver</u>{
	<em>@override</em>
	<em>void</em> <em>didPush</em>(<q>Route</q> <u>route</u>, <q>Route</q> <u>previousRoute</u>) {
	<em>super</em>.<em>didPush</em>(<u>route</u>, <u>previousRoute</u>); 		<em>// 当调用Navigator.push时回调</em>
		<em><u>RouteSettings</u> v</em> = <u>route</u>.<q>settings</q>;
	}
}
MaterialApp(
	<b>navigatorObservers</b>: 	[ <s>MyObserver</s>( ) ]
)